Molarity & Solutions

Welcome back, guys! In this new video, we're going to connect an old concept, molarity, with some new ones, solutions and intermolecular forces. Remember we talked about molarity a long time ago several videos back. Remember, molarity serves as the connection between the conversion of moles to liters and vice versa.
We're going to say for example if I give you 5.8 molar NaCl, that really means that I have 5.8 moles of NaCl per one liter. Remember, anytime they give you molarity, always assume that number they give you is in moles and it will be over 1 liter of solution.
Remember the formula for molarity is just molarity equals moles of solute over liters of solution.

MOLARITY represents the moles of solute dissolved per liters of solution.

These terms solute and solution are important. Remember, we have mixtures. Mixtures can be either homogenous or heterogeneous. Here we’re saying a typical mixture consists of a smaller amount of one substance, which is called the solute. Remember, the solute is the portion of our entire amount of liquid that is smaller in amount and it’s dissolved in a much larger type of substance called the solvent.
Remember, it’s solute combined with the solvent and together they form a solution. We're going to say that a mixture can come either as heterogeneous or homogeneous. A solution is a special type of homogeneous mixture. The solute completely dissolves. Why? Because the solute and the solvent are both either the same polarity or they have the same intermolecular force. That's what connects us to this theory of likes dissolving likes.
We're going to say according to the theory of likes dissolve likes, compounds with the same intermolecular force or polarity will dissolve into each other to give us our solution. Remember, we’ve talked about the intermolecular forces. There are five types but the four major ones are ion-dipole, the interaction of ions from ionic compounds with a polar solvent such as water, that’s the strongest type. We also have hydrogen bonding. Anytime H is connected to after F, O, or N, we’re going to have hydrogen bonding. Then we have dipole-dipole. Dipole-dipole exists for polar covalent compounds.
In between dipole-dipole and the weakest one, there’s another force called dipole-induced-dipole. This one is not as major as before that we're talking about, but it is considered one of the intermolecular forces. Dipole-induced-dipole is when we have a polar compound interacting with a non-polar compound. Finally, our last intermolecular force which is the weakest force is London dispersion or Van Der Waals or induced-dipole induce-dipole. Remember, the last force is the weakest force. It has these three names that we can give it. If you don't quite remember that, go back to the previous videos and look at intermolecular forces and polarity to help you guide you on which type of force a compound has.

A pure solvent with similar polarity can successfully dissolve a solute to create a solution.

Example #1: Butane, a nonpolar organic compound, is most likely to dissolve in: